Biomolecular charges influence the response of surface plasmon resonance biosensors through electronic and ionic mechanisms

0504701 - ÚFE 2020 RIV NL eng J - Journal Article
Šípová, Hana - Jurgová, Ludmila - Mrkvová, Kateřina - Lynn, Nicholas Scott - Špačková, Barbora - Homola, Jiří
Biomolecular charges influence the response of surface plasmon resonance biosensors through electronic and ionic mechanisms.
Biosensors and Bioelectronics. Roč. 126, 1 February (2019), s. 365-372. ISSN 0956-5663. E-ISSN 1873-4235
R&D Projects: GA ČR(CZ) GBP205/12/G118
Institutional support: RVO:67985882
Keywords : Self-assembled monolayers of alkanethiols * Biomolecules * Surface charge
OECD category: Optics (including laser optics and quantum optics)
Impact factor: 10.257, year: 2019
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0956566318308893?via%3Dihub

Surface plasmon resonance (SPR) biosensors have become an important label-free optical biomolecular sensing technology and a 'gold standard' for retrieving information on the kinetics of biomolecular interactions. Even though biomolecules typically contain an abundance of easily ionizable chemical groups, there is a gap in understanding of whether (and how) the electrostatic charge of a biomolecular system influences the SPR biosensor response. In this work we show that negative static charge present in a biomolecular layer on the surface of an SPR sensor results in significant SPR spectral shifts, and we identify two major mechanisms responsible for such shifts: 1) the formation of an electrical double layer (ionic mechanism), and 2) changes in the electron density at the surface of a metal (electronic mechanism). We show that under low ionic strength conditions, the electronic mechanism is dominant and the SPR wavelength shift is linearly proportional to the surface concentration of biomolecular charges. At high ionic strength conditions, both electric and ionic mechanisms contribute to the SPR wavelength shift. Using the electronic mechanism, we estimated the pKa of surface-bound carboxylic groups and the relative concentration of the carboxyl-terminated alkanethiols in a binary self-assembled monolayer of alkanethiols. The reported sensitivity of SPR to surface charge is especially important in the context of biomolecular sensing. Moreover, it provides an avenue for the application of SPR sensors for fast, label-free determination of the net charge of a biomolecular coating, which is of interest in material science, surface chemistry, electrochemistry, and other fields.
Permanent Link: http://hdl.handle.net/11104/0296281